Hi Elliot! After signing into WBF using your username and password, you can click on my name, then the silhouette icon "View Profile", and finally the tab "About Me" to see a detailed list of the components in my system.
I confess that I'm actually taking an expensive wager that the addition of the Ayre KX-R Twenty (to be delivered in March) will enable my Select DAC II to reach the next level of performance in expressing even wider dynamic swings, particularly in the low end, and introduce a balance to music which more closely resembles the effortless and exciting dynamic range present in live instruments.
Please don't belittle the more mainstream audio companies, but this video by PS Audio's Paul McGowan describes well what one should expect to hear with the addition of a preamp to help the source component better deliver the requisite dynamic swing(s) in current. Warning: product endorsement contained within!
https://www.youtube.com/watch?v=Dh27E7YKN9s
Here are the measurement of the Ayre preamplifier, as published in Stereophile - not too shabby!
https://www.stereophile.com/content/ayre-acoustics-kx-r-twenty-line-preamplifier-measurements
To help me have some basis for comparison, I have requested MSB to provide me with quantitative data on the ability (%THD, frequency, voltage) of the Select II's output section to deliver current into challenging loads of 600ohms, as well as a more modest 10Kohms (into the full spectrum of 10Hz to ~48kHz across a range of voltage outputs, as well as a 19kHz+20kHz IM graph at full output), but I'm still waiting. My JRDG 725 S2s have an input impedance of 40Kohms which is on the low side for solid state amps, and I want to verify for myself that the Select II indeed has sufficiently abilities to qualify as a bona-fide standalone preamplifier. I'm one of the select (no pun intended) owners of MSB's hyper-expensive, US$108,000 retail price, top-of-the-line, state-of-the-art, "you can't touch this, wannabes!" DAC, WITH purportedly an output section rivaling (and obviating the need for) a standalone preamp - so I hope my request is a very reasonable one!
I see that the CH Audio M1 has a nominal input impedance of 95Kohms (balanced), which is more than double those of my amp. For reference, the KX-R Twenty's input impedance is 2,000Kohms which is significantly less demanding for front end components to drive. The progression of higher and higher input impedances between components is the way it SHOULD be - the role of the preamplifier is (among other things) to preserve the fidelity of the line level input signal while performing as a buffer to deliver sufficient current into the power amplifier's inputs.
Here's an EXCELLENT video by Paul McGowan on the principles behind understanding input and output impedance coupling between source components, preamps, and power amps:
https://www.youtube.com/watch?v=6HGS6W7ZiGY
I would like to extend a big invitation to all WBF members and readers to share their experiences with either going direct or inserting a preamp between their DACs and their power amps, and articulate what you heard !